Ship HistoryBuilt by Osaka Iron Works. Laid down on August 14, 1936. Launched May 11, 1937. Completed August 31, 1937. Built as a whale oil factory ship for Nippon Suisan Kabushiki Kaisha (Japan. Fisheries Co., Ltd.) of Tokyo. The stern read "Tonan Maru No. 2 Tokio" in English and kanji. Amidship was a large Japanese flag insignia, to indicate neutrality and a large dot in a circle on the stack. On September 26, 1937, departs Japan for whaling in the Antarctic Ocean.

Wartime History
On February
22, 1941 in the Antarctic Ocean, German Auxiliary Cruiser Komet (HSK-7), searching for the Anglo-Norwegian whaling fleets in the area spots Tonan Maru No. 2 and Nisshin Maru, and hails the ship, learning Anglo-Norwegian whaling ships are further west.

On October 10, 1941 requisitioned by the Japanese Navy. During November, converted to a tanker capable of carrying 169,425 barrels of fuel (in 42 gallon barrels) or 23,114-tons of crude oil. Armed with two deck guns, machine guns and depth charges for defense.

Wartime HistoryParticipated in the Japanese landing at Kuching. On December 23, 1941 damaged by Dutch submarine. Afterwards, repaired and returned to duty.

On October 10, 1942, being used to ferry aircraft off Kavieng. Hit by a torpedo fired by USS Amberjack (SS-219) and sunk in Kavieng Harbor and another torpedo hit Tenryu Maru moored alongside. During the remainder of the month into November, Japanese pump out and refloat the ship and perform emergency repairs on site.

Departed on November 26 towed by Suwa Maru, but the effort is unsuccessful and both return the same day. Departs again on December 6, arrives at Truk five days later and undergoes more repairs, likely performed by Akashi. On December 16 departs Truk towed by Suwa Maru with tug Nagaura on the starboard side and another on the port side, plus escorting destroyer Yuzuki. On December 27 Yamagumo relieves Yuzuki, arrives Yokohama on December 30.

During 1943, drydocked and repaired.

By September 4, returns to Truk Lagoon as a static oil storage ship, and removed from Navy service on September 25 and returned to prewar owner, Nippon Suisan Kabushiki Kaisha.

On February 9, 1944 off southern Indochina enroute to Nagasaki. Five torpedoes were fired by USS Bonefish (SS-223), four are claimed as hits and damages her at roughly 11-30N, 109-08E. Towed to Singapore Seletar Naval Base for repairs by No. 101 Repair Unit during February to April 1944.

On May 7, departs Singapore with convoy SHIMI-02 arriving at Miri on May 12.

On August 20, departs Keelung, Formosa with convoy TAMO-23.

Sinking HistoryOn August 22, 1944 at 1900 while in the South China Sea, USS Pintado (SS-387) fires two spreads of 10 torpedoes, two hit Tonan Maru No.2 causing the ship to burn for three hours then sink at roughly then sinks at 29-53N, 125-19E. Four crew were killed in the sinking. This ship was one of the largest cargo ships sunk by a USN submarine during the war.

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